Gliederung

Objective: Epidural fibrosis is one of the main reasons for the failed back surgery syndrome following lumbar disc operations and there is no satisfactory therapeutical approach so far. Rapamycin, a fungal-derived antibiotic, is used in transplantation medicine to prevent host-versus-graft reactions by its considerable antiproliferative capacity. The objective of the current study was to evaluate the effects of Rapamycin in the prevention of postoperative epidural fibrosis in a rat laminectomy model.

Methods: 10 Wistar rats received an epidural deposit of Rapamycin in a concentration of 100Âµg/ml after bisegmental laminectomy at noncontiguos sites. Control animals (n=10) were treated with an equal amount of saline. Twelve weeks later animals were perfused and laminectomy sites examined histologically for quantitative estimation of epidural fibrosis.

Results: Following saline administration, there was a widespread epidural fibrosis extending beyond the margins of the laminectomy site. The dura showed fibrotic thickening and was broadly adherent to the surrounding tissues. On the other hand, Rapamycin lead to a marked reduction of the epidural fibrosis with only loosely arranged areolar tissue found between the thecal sac and the solid scar covering the osseous borders of the laminectomy, thus maintaining the mobility of the thecal sac and nerve roots. The dura itsself exhibited no fibrotic changes. Interestingly, wound healing was unaffected by Rapamycin.

Conclusions: Rapamycin proved to effectively prevent epidural epidural fibrosis. In addition to other antiproliferative agents like Mitomycin C, the additional antiinflammatory features of Rapamycin may augment its impact on epidural scar formation by inhibition of and reduced systemic toxicity.